colonial waterbirds nesting on the niagara river, 1976-2011. dave moore 1 francie cuthbert 2 chip...
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![Page 1: Colonial Waterbirds Nesting on the Niagara River, 1976-2011. Dave Moore 1 Francie Cuthbert 2 Chip Weseloh 1 Linda Wires 2 Niagara River RAP Implementation](https://reader030.vdocuments.site/reader030/viewer/2022032705/56649db35503460f94aa3b9c/html5/thumbnails/1.jpg)
Colonial Waterbirds Nesting on the Niagara River, 1976-2011.
Dave Moore1
Francie Cuthbert2
Chip Weseloh1
Linda Wires2
Niagara River RAP Implementation Committee Session10 Apr. 2013
Niagara College, Niagara-on-the-Lake, ON
1Canadian Wildlife Service2University of Minnesota
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Objective of surveys:
• To visit all islands on the Great Lakes and to census all species of colonial waterbirds that nest there (n=16).
They are conducted at approx. 10 year intervals:
Census 1 = 1976-80
Census 2 = 1989-91
Census 3 = 1997-2000
Census 4 = 2007-09
The Great Lakes Bi-national Decadal Colonial Waterbird Survey
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Great Black-backed Gull Herring Gull
Ring-billed Gull
Common Tern Caspian Tern
Double-crested Cormorant
Great Blue Heron Great Egret
Black-crowned Night-Heron
The Great Lakes Bi-national Decadal Colonial Waterbird Survey
Forster’s Tern
Black Tern
American White Pelican
• SNEG• CAEG• LBHE• BOGU• LIGU
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Methods• Census nests late in incubation or brooding
• Count all AONs
Approximate Census Timing:
8-30 May = Gulls (& scouting for other species)
1-7 June = Common & Caspian Terns
10-30 June = Cormorants and Herons
Census Methods:
Preferred Method = Ground count (of individual nests)
Other Methods = - extrapolation from ground counts - boat estimates - aerial surveys - estimates from aerial photographs
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Niagara River – colony distribution
Lake Ontario
Niagara River
Lake Erie
USACanada
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Niagara River – abundance & trendsDouble-crested Cormorant
2
3
3
4
Nes
ts
0
200
400
600
800
1000
1200
1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
USA Canada
3
5
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Niagara River – abundance & trendsBlack-crowned Night Heron
0
100
200
300
400
500
1976-80 1989-91 1997-99 2007-10
Canada USA
1
3
3
2
1
1
Nes
ts
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0
20
40
60
80
1976-80 1989-91 1997-99 2007-10
Canada USA
Niagara River – abundance & trendsGreat Blue Heron
0 0
1
1Nes
ts
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0
10
20
30
1976-80 1989-91 1997-99 2007-10
Canada USA
Niagara River – abundance & trendsGreat Egret
0 0
5
1
Nes
ts
*
*17 nests at 2 sites in Canada in 2012
1
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0
100
200
300
400
500
1976-80 1989-91 1997-99 2007-10
Canada USA
Niagara River – abundance & trendsCommon Tern
2
3
5
4
Nes
ts
1
3
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0
100
200
300
1976-80 1989-91 1997-99 2007-10
USA Canada
Niagara River – abundance & trendsHerring Gull
3
25
13
Nes
ts
1
52
3
3 3
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0
5,000
10,000
15,000
20,000
1976-80 1989-91 1997-99 2007-10
USA Canada
Niagara River – abundance & trendsRing-billed Gull
1
1
52
Nes
ts
1
2
2
4
6
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Niagara River – abundance & trends
0%
20%
40%
60%
80%
100%%
to
tal
nes
tsSpecies composition
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Niagara River – staging & over-wintering
• 1st site in NA to receive “Globally significant IBA” designation
• Important over-winter feeding area for 100,000+ gulls (daily)
• 19 species have been recorded (14 spp. on a single day)
• Two species occur in globally significant numbers:
• 100,000 Bonaparte’s Gulls (20% world population) pass through annually; daily mean =10,000, maximum = 40,000
• Herring Gulls – daily mean = 20,000, maximum = 50,000
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Niagara River – staging & overwintering
• Ring-billed Gull -- 18,000-27,000 individuals per day (fall / winter)
• Common Tern – 5,000+ individuals in Niagara Gorge during spring migration / staging
• Waterfowl – • daily totals of 20,000 individuals of 20 species
• significant numbers of Canvasback, Common Merganser, Greater Scaup & Common Goldeneye
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0
0.2
0.4
0.6
LH LSC DR LE NR LO SLR
How important are rivers to maintaining GLs waterbird diversity?
6
5
77
Water body (upstream downstream)
Diversity / Richness
*
Shan
non-
Wie
ner I
ndex
(H’)
9
1311
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0%
20%
40%
60%
80%
100%
FOTE BLTE GBBG BCNH RBGU COTE GBHE DCCO GREG HERG CAEA CATE LBHE SNEG
% n
ests
on
conn
ectin
g ch
anne
ls
Connecting channels represent ~2% of the total area downstream of the St. Marys River
How important are rivers to maintaining GLs waterbird diversity?
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Summary• Most species are more numerous on US side of river; BCNHs the exception
• herons, terns and cormorants have increased since monitoring began; the two gulls show inverse-U pattern, but consistent with GLs-wide trends
• overall healthy waterbird community on Niagara River; status ‘improving’ overall
• Diversity lower on connecting channels than adjacent lakes• Lowest on Detroit River, highest on SLR; NR had 2nd highest diversity
• For most species, abundance is disproportionately higher on connecting channels than predicted by their area; rivers very important for some species
• NR has continental significance as an overwintering / migratory staging area for some species